Quote:
Originally Posted by Snappy
Ok but at what depth does their par loose penetration value?
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hmm I was going to make some smart a$$ remark about T5s here, but there is something that bugs me here and because of it no one can answer your question.
it is fine to say a bulb will produce 330PAR or 400 or 800 ect.. but at what distance and through what?
T5s have a fairly rapid drop off, but is this realy true... nope, it only seams that way because of some of the stupid ways people are rating bulbs. same thing happened with MH and it lead a lot of people to thing they were getting something better than they were (IE when the DE bulbs first came out) light is light and it loses intensity with distance at about the same rate weather it is VHO, T5, MH, LED. but alot of people do measurments from 1 or 2" away from the bulb wich is useless as if you look at the loss of intensity over distance for a rough guess say it will lose 1/2 the value over 4X the distance (don't quote me on that I can't remember the exactr ration but this is for an explanation)
so if you measure the PAR at 1" and get 1000 PAR, then measur at 4" you should get 500, at 20" you should have 250 ect... so now this has been exploited by fudging the distance by different manufactures.. if I do the same measurments at 2" I would get 750 as a start, but at 8" I would get 375 which is the same as you would get in the first senerio at 8" but which one sounds better.
there needs to be a standard brought in between all bulbs MH, Flouressent, LED, ect.. and as far as I am concerned any measurment taken under 10" is useless for comparasons as the numbers are so large everything looks good.
I think a good way of measuing would be to take a PAR reading at 10", then one at 20", and one at 30" this would give you some good referance numbers for any common tank depth and give you a very good idea of the amount of drop off asociated with the light bulb.
personaly I am putting LED over my next tank.. got some of the stuff on order already.. going to cost me about 500.00 to build it but it should last 12 years or more and give me an ouput comparable or higher than a 250watt DE fixture with the consistant lighting that T5s give you. oh and I will be able to change my color with two dials. so if I get tired of 20K, I can change it to 10K, or 11K, or 12K, or maybe 12.5 ect.. you get the idea
Steve